Synonyms of arguable

2 Syllables
dubious, viable
3 Syllables
credible, tenable, rational, workable, unproven, feasible
4 Syllables
questionable, believable, defensible, defendable, debateable, controversial, debatable, reasonable, problematic, conceivable, disputable, assertable, unconfirmed, maintainable, sustainable, supportable
5 Syllables
unsubstantiated, controvertible, imaginable